Datasheet BD70522GUL (Rohm) - 6

BD70522GUL Detailed Descriptions 1. Constant ON-Time (COT) Control
The COT control topology supports CCM (Continuous Current Mode) for medium and high load conditions and DCM (Discontinuous Current Mode) for light load conditions. The ON-Time is set in proportion to the output voltage (VOUT), and in inverse proportion to power supply voltage (VIN). Therefore, when in CCM, even if VIN or VOUT settings changes, the IC always operates in a constant frequency 1MHz (Typ) approximately. If the load current decreases, the IC enters DCM seamlessly to maintain high efficiency down to very light loads, and the switching frequency varies approximately linearly with the load current.
2. 100%ON Mode
When VIN gets close to VOUT, the IC stops switching and starts 100% duty cycle operation. It connects the output to the input via the inductor and the internal high side MOSFET switch, when VIN falls below the 100%ON Mode Enter Threshold (V100THM). And when VIN increases and exceeds the 100%ON Mode Release Threshold (V100THP), the IC starts to switch again. VIN VOUT Soft 100% 100% Start MODE MODE V 250mV(Typ) 100THP V100THM 200mV(Typ) VPGTH 95%(Typ) VPGHYS 5%(Typ) VUVLORLS VUVLO 2.5V(Typ) 2.4V(Typ) PG t ① ① ① ① : Soft Start End ① ① ① ’ ① : VIN①V100THP① ① ’① VIN①V100THM High Low Low t Figure 4. 100% ON Mode Transition
3. Ultra Low Power (ULP) Mode
2 comparators are used in this IC for monitoring VOUT. One is main comparator (Main Comp) and the other is ULP comparator (ULP Comp). The transition from normal mode to ULP mode is judged pulse by pulse. While the Main Comp or the ULP Comp detects the decrease in VOUT, the LX node switches for one pulse, then becomes high impedance. If the high impedance state lasts over 8μs, the IC transits from normal mode to ULP mode. In ULP mode, the Main Comp and the Power Good comparator (PG Comp) are disabled to reduce the current consumption. And when the ULP Comp detects the decrease in VOUT, the Main Comp and the PG Comp are enabled, and the IC transits from ULP mode to normal mode. 8us 8us 8us normal mode ULP mode normal mode ULP mode normal mode Main Comp: ON Main Comp: OFF Main Comp: ON Main Comp: OFF Main Comp: ON PG Comp: ON PG Comp: OFF PG Comp: ON PG Comp: OFF PG Comp: ON Figure 5. Transition between Normal Mode and ULP Mode www.rohm.com
TSZ02201-0Q1Q0AJ00400-1-2
© 2017 ROHM Co., Ltd. All rights reserved. 6/24 TSZ22111 • 15 • 001
21.Aug.2017 Rev.002
Document Outline General Description Features Applications Key Specifications Package Typical Application Circuit Contents Pin Configuration Pin Descriptions Block Diagram Absolute Maximum Ratings Thermal Resistance Recommended Operating Conditions Electrical Characteristics Detailed Descriptions Typical Performance Curves Figure 7. Efficiency vs Output Current Figure 8. Efficiency vs Output Current Figure 9. Efficiency vs Output Current Figure 10. Efficiency vs Output Current Figure 11. Output Voltage vs Output Current Figure 12. Output Voltage vs Output Current Figure 13. Output Voltage vs Output Current Figure 14. Output Voltage vs Output Current Figure 15. Switching Frequency vs Output Current Figure 16. Switching Frequency vs Output Current Figure 17. Switching Frequency vs Output Current Figure 18. Switching Frequency vs Output Current Figure 19. Output Ripple Voltage vs Output Current Figure 20. Output Ripple Voltage vs Output Current Figure 21. Output Ripple Voltage vs Output Current Figure 22. Output Ripple Voltage vs Output Current Figure 23. Load Transient Response Figure 24. Load Transient Response Figure 25. Load Transient Response Figure 26. Load Transient Response Figure 27. Line Transient Response Figure 28. Line Transient Response Figure 29. Line Transient Response Figure 30. Line Transient Response Figure 31. Line Transient Response Figure 32. Line Transient Response Figure 33. Line Transient Response Figure 34. Line Transient Response Figure 35. Startup Figure 36. Startup Figure 37. Shutdown Figure 38. Shutdown Figure 39. Input Voltage Ramp Up/Down Figure 40. Input Voltage Ramp Up/Down Figure 41. Input Voltage Ramp Up/Down Figure 42. Input Voltage Ramp Up/Down Timing Chart Application Examples I/O Equivalence Circuits Operational Notes 1. Reverse Connection of Power Supply 2. Power Supply Lines 3. Ground Voltage 4. Ground Wiring Pattern 5. Recommended Operating Conditions 6. Inrush Current 7. Operation Under Strong Electromagnetic Field 8. Testing on Application Boards 9. Inter-pin Short and Mounting Errors 10. Unused Input Pins 11. Regarding the Input Pin of the IC 12. Ceramic Capacitor 13. Area of Safe Operation (ASO) 14. Thermal Shutdown Circuit(TSD) 15. Over Current Protection Circuit (OCP) 16. Disturbance Light Ordering Information Marking Diagram Physical Dimension and Packing Information Revision History